Electromotive drive, in particular blower drive

ABSTRACT

An electromotive drive being a commutator motor has a motor shaft being rotatably mounted on axially opposite sides in shaft bearings which are each covered by an end plate. A damping system for damping sound is arranged on that bearing side, which is averted from the end plate, of at least one of the shaft bearings. The damping system has an annular sealing disk and an annular sliding disk with an integrated spring element.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation application, under 35 U.S.C. §120, of copendinginternational application No. PCT/EP2013/001539, filed May 24, 2013,which designated the United States; this application also claims thepriority, under 35 U.S.C. §119, of German patent application No. DE 102012 010 480.4, filed May 26, 2012; the prior applications are herewithincorporated by reference in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to an electromotive drive. A drive of this kind isknown from international patent disclosure WO 2010/075844 A2.

In an electromotive drive of this kind, which often drives a fanimpeller of a blower in a heating and air-conditioning system of a motorvehicle, the motor shaft of the electric motor is rotatably mounted insliding bearings, which are configured as cup-and-ball bearings, both onthe brush system side (BS), on which commutator laminations of the motorare arranged. The brushes make contact with the commutator laminations,and also on the opposite side (AS). The cup-and-ball bearings arepressed against an end plate by a clamping frame. The motor shaftprojects out of the end plate which is close to the commutator by way ofa shaft section on which the fan impeller is fastened by its centralhub.

In order to avoid undesired noise on account of the axial play of themotor shaft and therefore of the motor rotor/impeller system in anelectromotive drive of this kind, in the case of the drive known from WO2010/075-844 A2 a damping system for damping sound is arranged at leaston that bearing side, which is averted from the end plate, of theBS-side shaft bearing. The damping system has a sealing disk or annularsealing disk and a sliding disk (thrust washer) or annular sliding diskwith sliding properties. A corrugated spring, which is in the form of aspring ring and is mounted on the motor shaft, is inserted between thesealing disk and the sliding disk as a spring element. The dampingsystem also has an annular damping element on that side of the sealingdisk which faces the shaft bearing. In the assembled state of thedamping system, the corrugated spring is situated in an annular spacewhich is formed between the damping element of the sealing disk and themotor shaft, and therefore the damping element coaxially surrounds thecorrugated spring.

The damping system serves to reduce the sound level, in particular ofstop noises which are caused by bearing play, but additionally to dampwhat are known as U tones (whining noises) which are caused byoperation-related disturbances with each revolution of the motor andassociated resonance phenomena.

SUMMARY OF THE INVENTION

The invention is based on the object of improving an electromotive driveof the kind cited in the introductory part in respect of its dampingsystem.

To this end, the electromotive drive has a commutator motor. A motorshaft of the commutator motor is rotatably mounted on axially oppositesides in shaft bearings which are each covered by an end plate. Theelectromotive drive further has a damping system for damping sound onthat bearing side, which is averted from the end plate, of at least oneof the shaft bearings. The damping system has an annular sealing disk,an annular sliding disk and a spring element which is integral with theannular sliding disk. In other words, the damping system has an annularsealing disk and an annular sliding disk with an integrated springelement.

The damping system expediently additionally has an annular dampingelement which is provided on the inner side of the annular sealing disk,which inner side faces the shaft bearing. A clamping frame which isplaced between the shaft bearing and the damping system is supported,over the periphery, on the end plate. Owing to the use of a clampingframe which is known per se, which is placed between the shaft bearingand the damping system and which is supported, over the periphery, onthe end plate, the shaft bearing, which is expediently configured as acup-and-ball bearing, is reliably pressed in the direction of the endplate which is situated opposite the damping system.

In an advantageous refinement, the spring element is realized in theform of spring arms which are integrally formed on the annular slidingdisk, that is to say are integral or form one piece with the annularsliding disk. The spring arms, which are preferably in the form of acorrugated spring, extend in the manner of an arc of a circle in thecircumferential direction of the annular sliding disk, wherein the freeends of the spring arms project out of the disk surface of the annularsliding disk, or the main body of the annular sliding disk, in the axialdirection.

According to an expedient development, the annular sliding disk, whichis also simply called the sliding disk in the text which follows, hasdriver sections which are in the form of a sector of a circle. In thisrefinement, the spring arms are integrally formed on mutually avertedcircle radii of the driver sections, wherein three spring arms and threedriver sections are preferably alternately arranged in a uniformlydistributed manner over the circumference of the annular sliding disk.

The driver sections particularly preferably project at least slightly inthe radial direction beyond the spring arms which are integrally formedon them. In connection with corresponding rotary bearing stops on theannular sealing disk, also called the sealing disk in the text whichfollows, these excess radial lengths of the driver elements serve thepurpose of rotary coupling between the sliding disk and the sealingdisk. To this end, the annular sealing disk suitably has, over thecircumference, a circumferential collar, at least one rotation stop forthe annular sliding disk being integrally formed on the inner face ofthe collar.

In the assembled state of the damping system, the annular sealing diskand the annular sliding disk are expediently latched to one another. Tothis end, an undercut contour is preferably integrally formed on thecollar of the annular sealing disk. In this preferred embodiment, thedriver sections of the annular sliding disk perform a dual function,specifically first they establish the latching to the annular sealingdisk, for which purpose the driver sections of the annular sliding diskengage behind the undercut contour of the annular sealing disk. Second,the driver sections form, by way of their sections which projectradially beyond the spring arms, a contact contour for the or eachrotation stop which is integrally formed on the collar of the annularsealing disk.

In the locked state of the sliding disk to the sealing disk, the driverelements form a stop in the corresponding rotation direction of themotor or of the motor shaft as soon as the sections of the driverelements which project radially beyond the spring arms have passedbeyond or through the distance, the angular measurement of which amountsto 120° for example, between two rotation stops of the sealing disk whenfirst commissioned.

In an advantageous refinement, the spring arms are of a corrugatedconfiguration with free ends which are directed at least slightlyaxially to the disk surface of the annular sliding disk. The arm lengthof each of the preferably three spring arms is approximately one sixthof the circumference of the annular sliding disk. The sliding disk withthe spring element integrally formed on it is suitably composed of athermoplastic elastomer, in particular of Hytrel.

Mounting of the damping system on the motor shaft is expedientlyconfigured with a press-fit. In this case, the pressing force oradhesion of the sealing disk on the motor shaft is greater than that ofthe sliding disk with the integrally formed spring element. Owing to acertain ability of the sealing disk to slide on the motor shaft, atleast the sealing disk may be guided along the motor shaft axially inthe direction of the sliding disk which is integral with the springelement for the purpose of locking the two disks as they are beingconnected to the damping system.

Following a first relative rotation between the two disks, the rotationstop between the disks is reached, and therefore the two disks andtherefore the entire damping system then always sit firmly on the motorshaft and rotate with the motor shaft in relation to the stationaryshaft or cup-and-ball bearing. The collar which, to this end, isintegrally formed on the preferably shell-like sealing disk and isdirected toward the shaft bearing serves as an oil trap in order tocapture sliding bearing oil which is spun out as a result of thecentrifugal force and to return the oil to the bearing.

The suitable material of the sliding disk which is integral with thespring element is steel, and therefore the sealing disk with theintegrated spring element cannot shrink. This provides the advantage ofreliable latching to the annular sealing disk.

The advantages which are achieved by the invention are in particularthat, owing to the use of the damping system which is preferablyprovided at the two bearing points of the motor shaft of anelectromotive blower drive, first noises or tones which are generated byaxial shaft deflections and also by the rotor/impeller system and/orcommutator/brush system are considerably damped. Second, on account ofthe integral configuration of the annular sliding disk and of the springelement, the functions of vibration damping and axial mounting arecombined, wherein a damping system which contains comparatively fewparts is provided overall.

Owing to the number of components, this number being reduced incomparison to the prior art, of the damping system according to theinvention, also called damping assembly in the text which follows, thedamping system is of simple construction and, in particular, can beassembled in a particularly simple and fault-free manner. Therefore,identification of an incomplete assembly is simplified owing to theintegration of the spring element into the annular sliding disk or theintegral configuration of the annular sliding disk and spring element,especially since the spring element is not visible in the installedstate of the damping assembly.

Other features which are considered as characteristic for the inventionare set forth in the appended claims.

Although the invention is illustrated and described herein as embodiedin an electromotive drive, in particular a blower drive, it isnevertheless not intended to be limited to the details shown, sincevarious modifications and structural changes may be made therein withoutdeparting from the spirit of the invention and within the scope andrange of equivalents of the claims.

The construction and method of operation of the invention, however,together with additional objects and advantages thereof will be bestunderstood from the following description of specific embodiments whenread in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a diagrammatic, partial longitudinal sectional view through anelectromotive drive for a heating and air-conditioning system blower ina motor vehicle, having a BS-side cup-and-ball bearing and an AS-sidecup-and-ball bearing with a damping system according to the invention;

FIG. 2 is an exploded, perspective view of the damping system accordingto the invention with, in a direction of a motor shaft downstream of theBS-side cup-and-ball bearing, an annular sealing disk and an annularsliding disk with an integrally formed spring element;

FIG. 3A is a top plan view of the sliding disk which is integral withthe spring element;

FIG. 3B is a side view of the sliding disk which is integral with thespring element; and

FIG. 3C is an oblique perspective view of the sliding disk which isintegral with the spring element.

DETAILED DESCRIPTION OF THE INVENTION

Parts which correspond to one another are provided with the samereference symbols throughout the figures.

Referring now to the figures of the drawings in detail and first,particularly to FIG. 1 thereof, there is shown an electromotive drive inthe form of a commutator motor 1 having a motor housing (pole pot) 2, anumber of shell-like exciter or permanent magnets 3, which numbercorresponds to the number of poles of the motor 1, being mounted on theinside circumference of the motor housing. A motor shaft 4 carries, in amanner not illustrated in any detail, a rotor 5 of the commutator motor1, the rotor 5 being configured as a laminated rotor core with rotorwindings wound therein. A commutator 6 which is likewise mounted on themotor shaft 4 has commutator laminations 6 a with lamination connections6 b (FIG. 2) which are connected to the rotor windings of the rotor 5.Brushes make contact with the laminations 6 a of the commutator 6 in amanner known per se. This motor side is often also designated as a brushor brush system side or BS (BS-side) for short. The opposite side isdesignated AS (AS-side).

On the BS-side of the commutator motor 1, a BS-side end plate 7 isfastened to the motor housing 2 at the motor end which is close to thecommutator. An AS-side end plate 8 is fastened to the motor housing 2 atthe opposite end, which is remote from the commutator, of the motorshaft 4. The two end plates 7, 8 accommodate cup-and-ball bearings 9and, respectively, 10 in which the motor shaft 4 is rotatably mounted byan oil film. The two stationary cup-and-ball bearings 9, 10 are eachpressed against the respective end plate 7 and, respectively, 8 by aclamping frame 11, 12 and clamped. In the process, the clamping frame11, 12 is supported on the respective end plate 7 and, respectively, 8.

The commutator-side end of the motor shaft 4 projects out of the endplate 7 on the BS side by way of a sufficiently long shaft section 13,in order to receive a fan impeller of a heating and air-conditioningsystem blower of a motor vehicle in the manner known from FIG. 1 ofGerman utility model DE 295 13 633 U1, the fan impeller being pressed byway of its hub onto the section of the motor shaft 4 there. Thecommutator motor 1, which drives the fan impeller when it rotates,therefore serves as a blower drive.

As is shown comparatively clearly in FIG. 2, a damping system orassembly 14 is provided at least at the BS-side bearing point,preferably also at the AS-side bearing point. The damping system orassembly is mounted onto the motor shaft 4 on that bearing side, whichis averted from the respective end plate 7, 8, of the cup-and-ballbearing 9 and, respectively, 10. The damping system 14 absorbs the axialplay which extends in the longitudinal direction of the motor shaft 4.

The damping system 14 serves first to damp stop noises that are causedby the axial deflection of the system that is formed by the rotor 5 andthe commutator 6, including the motor shaft 4, the system also includingthe fan impeller in the case of a blower drive. The damping system 14therefore reduces the noise level and also damps those noises which areknown as U or whining tones which are generated by the commutator/brushsystem. The corresponding development of noise can be attributed todisturbances with each revolution of the motor, the disturbances beingcaused by the relative movement of the commutator laminations and thebrushes moving over them. These disturbances cause characteristic noisesat housing part-specific resonance points in the relatively largeplastic housing.

The damping system 14 is made up of an annular sealing disk 15, simplycalled the sealing disk in the text which follows, and an annularsliding disk 16, simply called the sliding disk in the text whichfollows, with an integrated spring element 17. The spring element 17,which contains three spring arms 17 a which are integral with thesliding disk 16, faces the respective cup-and-ball bearing, in this casethe cup-and-ball bearing 9. A defined spring path, which isapproximately 0.2 mm long, is formed between the sealing disk 15 and thesliding disk 16. In the assembled state of the damping system 14, thespring arms 17 a bear against the sealing disk 15. In this case, adamping element 18, which is integrally formed on the sealing disk 15 oris inserted into the sealing disk and is in the form of a ring,coaxially surrounds the spring arms 17 a.

The damping element 18 is preferably an integral constituent part of thesealing disk 15 and is composed of a damping material which iscomparatively soft in relation to the comparatively hard material of therest of the sealing disk 15. A shaft seal 19, which is likewise composedof the damping material and can likewise be integral with the rest ofthe sealing disk 15, engages around the motor shaft 4 and in the processforms a cylindrical or sleeve-like seal transition between the sealingdisk 15 and the motor shaft 4.

The approximately shell-like sealing disk 15 has a circumferentialcollar 15 a in order to capture sliding bearing oil, which has been spunout for operation-related reasons, in order to protect the commutator 6.The collar 15 a is additionally used first in order to latch the slidingdisk 16 with the integrated spring element 17 to the sealing disk 15. Tothis end, a preferably circumferential undercut contour 15 b isintegrally formed on the collar 15, the undercut contour extendingradially in the direction of the shaft 4. Second, cams 15 d on theinside, that is to say integrally formed on the collar inner wall 15 cor worked from the collar inner wall by shaping or deformation, serve asrotation stops for the sliding disk 16.

In the state in which the sealing disk 15 and the sliding disk 16 withthe integrated spring element 17 are latched to one another, driverelements 16 a, of which only one is designated in FIG. 2, engage behindthe undercut contour 15 b of the sealing disk 15. As a result, thesealing disk 15, which is pressed onto the motor shaft 4, can be axiallydisplaced in relation to the sliding disk 16, which is likewise pressedonto the motor shaft 4 but is practically immovable, and is thereforefixed to the sliding disk by latching.

As is shown comparatively clearly with reference to the sliding disk 16with the integrated spring element 17, illustrated in FIGS. 3A to 3C,the radially extending driver elements 16 a are offset through 120° inrelation to one another. The sliding disk has sector-like recesses 16 bbetween the driver elements 16 a, ring sections 16 d adjoining therecesses - toward the central disk opening 16 c in the radial directionR. The spring arms 17 a are integrally formed on the driver elements 16a in the region of their circle radii 16 e and extend into thesector-like recesses 16 b in the sliding disk 16 in the manner of an arcof a circle in a circumferential direction U of the sliding disk 16 withthe integrated spring element 17.

The connection between the spring arms 17 a and the driver elements 16 aof the sliding disk 16 is positioned in such a way that the driverelements 16 a project beyond the spring arms 17 a in the radialdirection R so as to form contact edges 16 f. In the latched state ofthe sealing disk 15 and the sliding disk 16, the contact edges 16 f formthe mating stop of the sliding disk 16 to the rotation stop of thesealing disk 15 in the form of the cams 15 d of the sealing disk.

As shown in FIGS. 3B and 3C, the spring arms 17 a of the spring element17, which is integral with the sliding disk 16, protrude out of theplane or surface 16 g of the sliding disk 16 in the axial direction A.In this case, the spring arms 17 a are configured in the manner of anarc of a circle in the circumferential direction U of the sliding disk16 and in the manner of a corrugation in the axial direction A. Thespring arms 17 a which are integral with the sliding disk 16 thereforeform a kind of annular spring element 17 with sinusoidal waves. In thiscase, the spring arm ends 17 b are oriented at least slightly toward thedisk top face 16 g over the course of the sinusoidal or corrugatedformation.

The following is a summary list of reference numerals and thecorresponding structure used in the above description of the invention:

-   1 Commutator motor-   2 Motor housing-   3 Exciter magnet-   4 Motor shaft-   5 Rotor-   6 Commutator-   7 BS-side end plate-   8 AS-side end plate-   9 Cup-and-ball bearing-   10 Cup-and-ball bearing-   11 BS-side clamping frame-   12 AS-side clamping frame-   13 Shaft section-   14 Damping system/assembly-   15 Sealing/annular sealing disk-   15 a Collar-   15 b Undercut contour-   15 c Collar inner wall-   15 d Cam/rotation stop-   16 Sliding/annular sliding disk-   16 a Driver element-   16 b Recess-   16 c Disk opening-   16 d Ring section-   16 e Circle radius-   16 f Contact edge-   16 g Disk top face/plane-   17 Spring element-   17 a Spring arm-   17 b Spring arm end-   18 Damping element-   19 Shaft seal-   A Axial direction-   R Radial direction-   U Circumferential direction

1. An electromotive drive being a commutator motor, the electromotivedrive comprising: shaft bearings; a motor shaft rotatably mounted onaxially opposite sides in said shaft bearings; end plates, each of saidend plates covering one of said shaft bearings; and a damping system fordamping sound disposed on that bearing side, averted from said endplate, of at least one of said shaft bearings, said damping systemhaving an annular sealing disk, a spring element and an annular slidingdisk facing one of said shaft bearings, said spring element being anintegral constituent part of said annular sliding disk.
 2. Theelectromotive drive according to claim 1, wherein said spring elementhaving spring arms running in a manner of an arc of a circle and are ina form of a corrugated spring are disposed along a circumference of saidannular sliding disk, said spring arms projecting out of a disk surfaceof said annular sliding disk in an axial direction.
 3. The electromotivedrive according to claim 2, wherein said annular sliding disk has driversections which are in a form of a sector of a circle.
 4. Theelectromotive drive according to claim 3, wherein: said annular slidingdisk having recesses formed therein; and said spring arms are integrallyformed on mutually averted circle radii of said driver sections andextend into said recesses in said annular sliding disk which aredisposed between said driver sections.
 5. The electromotive driveaccording to claim 4, wherein said driver sections project at leastslightly in a radial direction beyond said spring arms which areintegrally formed on them.
 6. The electromotive drive according to claim3, wherein three of said spring arms and three of said driver sectionsare alternately disposed in a uniformly distributed manner over acircumference of said annular sliding disk.
 7. The electromotive driveaccording to claim 3, wherein an arm length of each of said spring armsis approximately 1/6 of a circumference of said annular sliding disk. 8.The electromotive drive according to claim 2, wherein said spring armsare of a corrugated configuration with spring arm ends which aredirected at least slightly axially to a surface of said annular slidingdisk.
 9. The electromotive drive according to claim 1, wherein saiddamping system has an annular damping element on an inner side of saidannular sealing disk, said inner side facing one of said shaft bearings.10. The electromotive drive according to claim 3, wherein said annularsealing disk and said annular sliding disk are latched to one another.11. The electromotive drive according to claim 10, wherein said annularsealing disk has, over a circumference, a circumferential collar with anundercut contour integrally formed on it.
 12. The electromotive driveaccording to claim 11, further comprising at least one rotation stop forsaid annular sliding disk integrally formed on an inner face of saidcircumferential collar.
 13. The electromotive drive according to claim12, wherein said driver sections of said annular sliding disk firstengage behind said undercut contour to establish a latching connectionto said annular sealing disk, and second have a contact edge for saidrotation stop of said annular sealing disk.
 14. The electromotive driveaccording to claim 2, wherein said annular sliding disk with said springelement is composed of metal.
 15. The electromotive drive according toclaim 2, wherein said annular sliding disk with said spring element iscomposed of steel.